I come across faulty keys on my Kindle 3 recently.
When I press "r", "s" or "del", it will come with a dot.
For example, when I press "r", it appears as "r."
When I press "del", it will delete the letter before and show a "."
But the dot key itself is not working. Others are just fine.

I have no idea whether it's a software issue or hardware issue. I upgraded to Kindle 3.3 recently. After hard reset, the problem is still there. (after hard reset the system is still 3.3)